Data protocols are typically comprised of different protocol layers. Each layer represents a different level of abstraction of the information associated with the protocol. The protocols in existence today are vast and ever-expanding in terms of quantity and performance. Serial data protocols include, for example, SATA, Fibre Channel, serial attached SCSI (SAS), USB, FireWire, and the like. By way of other examples, protocols can include multiple input decoders such as SPI or I2C, or multi-lane hierarchical decoders such as PCIe and DisplayPort. Protocols need not be digital. For instance, analog TV signals and other non-digital hierarchical signals can also be classified as protocols.
Conventional protocol analyzers are specialized tools that are used to capture and analyze protocol information. The protocol analyzers can analyze, for example, a telecom signal, a bus signal, a network signal, or the like. However, current protocol analyzers have significant limitations. For instance, it is not possible to correlate protocol level information with physical layer signals or events. As buses, especially serial buses, become more predominate, users naturally want to see how protocol information is related to analog events.
Generally, a separate instrument such as an oscilloscope is needed to capture and analyze physical or analog layer signals and events. One of the strengths of an oscilloscope is the ability to record analog characteristics of the physical layer of a protocol. But oscilloscopes do not allow for navigation, visualization, or analysis of higher-level data protocols, nor the ability to link or otherwise correlate protocol level information to physical layer events. Thus, it is difficult or impossible to associate analog characteristics of the physical layer signal underpinning the protocol to higher-level information such as the different abstracted layers of the protocol. Moreover, there is no intuitive way to navigate the different protocol layers, nor associate items between the different layers.
Accordingly, a need remains for a protocol sensitive visual navigation apparatus, which provides the ability to correlate physical layer signals or events to protocol level information, thereby increasing an understanding of the overall protocol and associated layers and events. It would also be desirable for a test and measurement instrument such as an oscilloscope to include the protocol sensitive visual navigation apparatus so that a protocol can be comprehensively analyzed and protocol level events can be related to physical layer events.